Ultrasonic diagnostic apparatus

ABSTRACT

With respect to a scanning plane of a subject having been injected with a contrast agent, an ultrasound transmission section  6  transmits for a plurality of times an ultrasonic pulse of such an intensity capable of collapsing the contrast agent. An ultrasound reception section  5  receives an echo signal cluster from the subject based on the ultrasonic pulses, and generates a plurality of RF data items through addition of the echo signal cluster using an adder  5 C. Based on the plurality of RF data items, a TIC/MTT measurement section  25  measures a time intensity curve (TIC), and then measures a mean transit time (MTT) of the blood flow based on the time intensity curve for display on a display section  21.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Continuation Application of PCT Application No.PCT/JP02/08475, filed Aug. 22, 2002, which was not published under PCTArticle 21(2) in English.

This application is based upon and claims the benefit of priority fromprior Japanese Patent Application No. 2001-251766, filed Aug. 22, 2001,the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an ultrasonic diagnostic apparatuscapable of quantitatively assessing blood flow behaviors using acontrast agent for ultrasound.

2. Description of the Related Art

An ultrasonic diagnostic apparatus is medical image equipment with whichtomographic images of soft tissues beneath the body surface are derivedfrom a living body in a noninvasive manner by the ultrasonic pulse echomethod, and has been popular in the Departments relating to hearts,abdominal regions, and urinary, and the Department of obstetrics andgynecology. This ultrasonic diagnostic apparatus is, characteristically,smaller in size and lower in price than other types of medical imageequipment (e.g., X-ray diagnostic equipment, X-ray CT equipment, MRIdiagnostic equipment, nuclear medicine diagnostic equipment), capable ofreal time display, capable of offering a high level of safety withoutX-ray exposure, capable of blood flow imaging, and the like. Recently,the contrast echo has become popular with which more detailed diagnosticimages are derived by increasing echo effects of ultrasound thanks tothe contrast agent that has been injected into a subject. For example,with cardiac and abdominal organ examinations utilizing the contrastecho, the contrast agent for ultrasound is injected from a low-invasivevein to collect ultrasonic echo signals having intensified by thusinjected contrast agent. Generating diagnostic images based on such echosignals allows estimation of the blood flow behaviors in a more detailedmanner.

As the imaging technique is established in image diagnosis, thequantitative assessment using the contrast agent has become popular forstudy. The functional diagnosis through quantitative assessment hasbecome advanced especially in the field of nuclear medicine and othersin which pharmaceutical drug study utilizing metabolic functions isactive. Exemplarily in a circulatory system, myocardial functionalassessments are made utilizing a time intensity curve (TIC: TimeIntensity Curve) as a result of plotting time-varying intensityinformation. Resultantly derived thereby are the time in the contractionphase taken to reach the maximum contraction speed from the last periodof expansion, the maximum contraction speed, and the like. Needless tosay to the ultrasonic diagnostic apparatus, such a TIC is applicablealso to X-ray, X-ray CT, and MRI, all of which are operable using thecontrast agent.

As another type of quantitative assessment using the contrast agent,known is a technique of calculating a mean transit time (MTT: MeanTransit Time: in the below, referred to as “MTT”) of the blood flowusing the TIC. Such an MTT allows assessment of the blood flow behaviorsin organs, and measurement of the flow volume in a quantitative manner.Also in the ultrasonic diagnostic apparatus, quantitative analysis isbecoming possible, such as TIC measurement using the contrast agent, andMTT analysis based on the TIC.

FIG. 1 is a diagram for illustrating the MTT. In FIG. 1, in a case ofadministering the contrast agent on a continual basis, the MTT will bethe value to be derived in the following manner. That is, firstcalculated is an area S enclosed by a saturation value and a TIC betweenthe administration starting time of the contrast agent and the time ofreaching the saturation value, and the result is then standardized bythe saturation value. Herein, the area calculation and thestandardization may be executed in the reverse order, and if this is thecase, the TIC may be first standardized by the saturation value tocalculate the area.

The issue here is that, the contrast agent used for ultrasonic diagnosisis composed of very-small bubbles, and has such a peculiar physicalproperty that the contrast agent itself may be collapsed and vanished.Thus, simply applying the technique so far used with the MTT in otherdiagnostic apparatuses cannot realize the quantitative assessment withassured objectivity and accuracy. At present, the MTT in ultrasonicdiagnosis is under study quite actively. For example, as to suchproblems as effects of bioattenuation in any examination using thecontrast agent for ultrasound, and varying concentrations of thecontrast agent whenever it is used, a generally known solution thereforis standardization by saturation values.

However, the following problems are not yet solved to put the MTT intopractical use in the ultrasonic diagnostic apparatus, for example.

The first problem is the varying MTTs due to uneven beam shapes. To bespecific, generally, if the beam shapes are uneven in the depthdirection, assessing any two point regions different in beam shape willresult in varying volumes available for the very-small bubbles tocollapse and vanish. If this is the case, even if a TIC is plotted forregions different in beam shape with respect to organs having the samelevel of blood flow behaviors without depending on the depth, forexample, the resulting saturation values, i.e., maximum values, maystill vary. Thus, the standardized TICs show no coincidence, resultingin varying MTTs depending on the depth.

Moreover, using the contrast agent bubbles requires the longermeasurement time compared with TIC measurement with other types ofmedical equipment. In detail, responding to ultrasound exposure,very-small bubbles in thus exposed plane are collapsed and vanished.Therefore, for data acquisition within a sample time required forplotting a TIC, there requires another ultrasound exposure with a waituntil the very-small bubbles again fill the same exposed plane. With TICmeasurement in diagnosis utilizing flash echo imaging, there requires adata cluster corresponding to each intermittent time interval. Further,if temporal samplings are increased in number to plot a TIC, the crosssection under study has to be maintained longer by the time thusincreased corresponding to the time interval between the temporalsamplings. In an exemplary case where a TIC covering 20 [seconds] isplotted with the temporal samplings of every 1 [second], it simply takes20 [seconds] with X-ray enhanced and X-ray enhanced CT. On the otherhand, in a case of using the contrast agent for ultrasound, it takes$\begin{matrix}{{1 + 2 + 3 + \ldots + 18 + 19 + 20} = {210\quad\lbrack{seconds}\rbrack}} \\{= {3.5\quad\lbrack{minutes}\rbrack}}\end{matrix}$This is because every time scanning is done, the very-small bubblesbeing the contrast agent collapse and vanish, and thus resetting isrequired. During that time, the operator thus has to maintain the crosssection. If so, however, it is difficult to securely keep the scanningcross section at the same position. There is a possibility of checkingthe cross section by performing so-called monitor mode scanning with lowsound pressure level not to collapse nor vanish the very-small bubbles,however, this requires to retain the probe for a long absolute time.Still more the long-time administration of the contrast agent forultrasound, and the resulting long-time examination will bedisadvantageous for doctors, operators, and patients.

Furthermore, there may be a case where the very-small bubbles are notfully collapsed or vanished if the contrast agent is of a type hardlycollapsing or vanishing, if the contrast agent is high in concentration,or if the transmission sound pressure is low. As such, if the bubblesare not fully collapsed or vanished, it results in the followingdrawbacks.

Firstly, the resulting MTTs will vary depending on the depth. This isbecause, even if the blood flow rate of the blood flow is constantwithout depending on the depth in any organ under study, when theselection position of ROI (Region of Interest) changes in the depthdirection, the ratio of the very-small bubbles collapsing and vanishingalso changes depending on the depth. This is because the transmissionultrasound is attenuated due to reflection and scattering in the processof passing over the very-small bubbles and collapsing those, or in theprocess of passing through the living body. Secondly, if the very-smallbubbles are remained, it means that a signal derived by the nextintermittent transmission resultantly includes an offset of theremaining bubbles. Thus, the flow volume of the very-small bubbles,i.e., blood flow rate, cannot be correctly obtained, thereby failing inderiving correct MTTs after all. Thirdly, as described in the foregoing,due to attenuation of the transmission ultrasound or attenuation of thereflected ultrasound, nearly no signal will be returned if the depthreaches at a certain point. Thus, due to a so-called shadowingphenomenon in which shadows are cast on images, there exists regionsbeing not accessible.

The present invention is proposed in consideration of the abovecircumstances, and an object thereof is to provide an ultrasonicdiagnostic apparatus with which effects caused by the depth can bereduced, and MTTs can be derived with assured accuracy and with highreproducibility through short-time scanning.

BRIEF SUMMARY OF THE INVENTION

To achieve the above object, the present invention takes the followingmeans.

A first viewpoint of the present invention is directed to an ultrasonicdiagnostic apparatus, including: an ultrasonic probe for transmittingultrasound to a subject having been injected with a contrast agent, andreceiving ultrasonic echo from the subject; a driving signal generatorfor generating a driving signal for driving the ultrasonic probe; acontrol unit for performing scanning for a plurality of times withultrasound of such a high intensity that the contrast agent is collapsedat a time-varying time interval after the contrast agent is injected,and controlling the driving signal generator based on a scan sequence inwhich the time interval after the scanning performed for the initialtime is set to be 5 seconds or shorter; and a processor for plotting atime-varying concentration graph of the contrast agent based on theultrasonic echo.

A second viewpoint of the present invention is directed to an ultrasonicdiagnostic apparatus, including: an ultrasonic probe for transmittingultrasound to a subject having been injected with a contrast agent, andreceiving ultrasonic echo from the subject; a driving signal generatorfor generating a driving signal for driving the ultrasonic probe; acontrol unit for controlling the driving signal generator based on ascan sequence in which scanning is performed for a plurality of timeswith a constant time interval after the contrast agent is injected; anda processor for plotting a time-varying concentration graph of thecontrast agent based on a plurality of cumulative values or averagevalues of the ultrasonic echo as a result of the scanning performed forthe plurality of times.

A third viewpoint of the present invention is directed to an ultrasonicdiagnostic apparatus, including: an ultrasonic probe for transmittingultrasound to a subject having been injected with a contrast agent, andreceiving ultrasonic echo from the subject; a driving signal generatorfor generating a driving signal for driving the ultrasonic probe; acontrol unit for controlling the driving signal generator based on apredetermined scan sequence for plotting a time-varying concentrationgraph of the contrast agent; a signal processor for applying a detectionprocess and a logarithmic transformation process to the ultrasonic echo;an image generator for generating an ultrasonic image based on an outputof the signal processor; an antilogarithmic transformation unit forapplying an antilogarithmic transformation process to at least an outputsignal coming from either of the signal processor or the imagegenerator; and a processor for plotting a time-varying graph based onthe output signal coming from the antilogarithmic transformation unit.

A fourth viewpoint of the present invention is directed to an ultrasonicdiagnostic apparatus, including: an ultrasonic probe for transmittingultrasound to a subject having been injected with a contrast agent, andreceiving ultrasonic echo from the subject; a driving signal generatorfor generating a driving signal for driving the ultrasonic probe; acontrol unit for controlling the driving signal generator based on apredetermined scan sequence for plotting a time-varying concentrationgraph of the contrast agent; a signal generator for generating a firstsignal as a result of a detection process and a logarithmictransformation process applied with respect to the ultrasonic echo, anda second signal as a result of the detection process applied withrespect to the ultrasonic echo; an image generator for generating anultrasonic image based on the first signal; and a measurement processorfor plotting the time-varying graph based on the second signal.

A fifth viewpoint of the present invention is directed to an ultrasonicdiagnostic apparatus, including an ultrasonic probe for transmittingultrasound to a subject having been injected with a contrast agent, andreceiving ultrasonic echo from the subject; a driving signal generatorfor generating a driving signal for driving the ultrasonic probe; acontrol unit for controlling the driving signal generator based on apredetermined scan sequence for deriving a time-varying concentration ofthe contrast agent; an image generator for generating an ultrasonicimage based on the ultrasonic echo; and a measurement processor forplotting a time-varying concentration graph of the contrast agent basedon the ultrasonic echo, and for compensating a mean transit time of ablood flow derived from the time-varying graph depending on ameasurement position depth.

A sixth viewpoint of the present invention is directed to an ultrasonicdiagnostic apparatus, including: an ultrasonic probe for transmittingultrasound to a subject having been injected with a contrast agent, andreceiving ultrasonic echo from the subject; a driving signal generatorfor generating a driving signal for driving the ultrasonic probe; acontrol unit for controlling the driving signal generator based on apredetermined scan sequence for plotting a time-varying concentrationgraph of the contrast agent; an image generator for generating anultrasonic image based on the ultrasonic echo; and a measurementprocessor for plotting the time-varying concentration graph of thecontrast agent based on the ultrasonic echo, and for compensating thetime-varying graph depending on a measurement position depth.

According to such structures, realized is an ultrasonic diagnosticapparatus with which MTTs can be derived with assured accuracy and withhigh reproducibility through short-time scanning.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a diagram for illustrating an MTT.

FIG. 2 is a block diagram showing the structure of an ultrasonicdiagnostic apparatus 100 of a present embodiment.

FIG. 3 is a flowchart showing the process procedure of TIC/MTTmeasurement to be executed by the ultrasonic diagnostic apparatus 100.

FIG. 4 is a conceptual diagram for illustrating the resulting TIC andMTT derived by the process of TIC/MTT measurement.

FIG. 5 is a conceptual diagram showing bioinformation MTB (Mean TransitBeat) measurable by a TIC/MTT measurement section 25.

FIGS. 6A, 6B, and 6C are all a conceptual diagram for illustrating acompensation process to be executed with respect to the resultantlyderived MTT. FIG. 6A is a schematic view of a beam profile in theslice-thickness direction. FIG. 6B is a diagram showing TICs (before andafter standardization) as a result of measurement using echo signalscoming from positions A and B, respectively, in FIG. 6A. FIG. 6C is adiagram showing MTTs derived by FIG. 6B.

FIG. 7 is a conceptual diagram for illustrating an area that ismeasurable by the TIC or MTT.

FIG. 8 is a conceptual diagram for illustrating the scan sequence to beexecuted by the present ultrasonic diagnostic apparatus, and the TIC asa result of measurement based on echo signals derived by the scansequence.

FIG. 9 is a conceptual diagram for illustrating the TIC/MTT measurementutilizing a monitoring mode.

FIG. 10 is a conceptual diagram for illustrating the effectiveinformation extraction process.

FIG. 11 is a block diagram showing the structure of the ultrasonicdiagnostic apparatus 100 according to a second embodiment.

FIG. 12 is a block diagram showing the structure of an ultrasonicdiagnostic apparatus 104 according to a third embodiment.

FIG. 13 is a block diagram showing the structure of an ultrasonicdiagnostic apparatus 106 according to a fourth embodiment.

FIG. 14 is a block diagram showing the structure of an ultrasonicdiagnostic apparatus 108 according to a fifth embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

In the below, first to fifth embodiments of the present invention aredescribed by referring to the accompanying drawings. Note that, in thefollowing description, any component sharing almost the same functionand structure will be provided with the same reference numeral, and willbe described again if necessary.

First Embodiment

First of all, described is the structure of an ultrasonic diagnosticapparatus 100 of a first embodiment by referring to FIG. 2. Theultrasonic diagnostic apparatus 100 of the present embodiment is the oneperforming TIC/MTT measurement utilizing RF data (data after phaseaddition) as will be described later.

FIG. 2 is a block diagram showing the structure of the ultrasonicdiagnostic apparatus 100. As shown in FIG. 2, the present ultrasonicdiagnostic apparatus 100 is structured by an electrocardiogram (ECG) 1,an ultrasonic probe 4, an apparatus body 22, an operation panel 15, andan input unit 35. In the below, each of those components will bedescribed.

The electrocardiogram (ECG: ElectroCardioGram) 1 measures a graph havingrecorded the time-varying electrical phenomena of a subject's heart,i.e., electrocardiogram. Electrocardiogram waveform signals detected bythe electrocardiogram 1 are forwarded to reference data memory 3 via anamplifier 2, and if required, forwarded to a display section 21 via amemory synthesis section 11 to be displayed as electrocardiogramwaveforms.

The ultrasonic probe 4 has a piezoelectric transducer as anelectroacoustic reversible transducer such as piezoelectric ceramics.Such a piezoelectric transducer is plurally arranged in parallel to beequipped at the tip of the probe 4.

The operation panel 15 is connected to an apparatus body 22, and isprovided with the input unit 35 (mouse 13, trackball 14, mode shiftswitch 16, keyboard 17, and others) for setting Region of Interest (ROI)to capture various instructions, commands, and information coming froman operator into the apparatus body 22.

The apparatus body 22 is provided with: the amplifier 2; the referencedata memory 3; an ultrasound reception section 5; an ultrasoundtransmission section 6; a receiver section 7; a B-mode DSC section 8; aCFM unit 9; a CFM mode DSC section 10; the memory synthesis section 11;frame memory 12; a timing signal generator 18; a trigger signalgenerator 19; a control circuit (CPU) 20; the display section 21; aTIC/MTT measurement section 25; a storage section 27; and a B-mode unit30.

The ultrasound transmission section 6 is provided with a pulse generator6A, a transmission delay circuit 6B, and a pulser 6C, and is connectedto the prove 4.

The pulse generator 6A repeatedly generates a rate pulse at a ratefrequency frHz (period: 1/fr second) of 5 kHz, for example. This ratepulse is split into the number of channels, and then forwarded to thetransmission delay circuit 6B. To the respective rate pulses, thetransmission delay circuit 6B provides the delay time needed to applybeam focusing with respect to the ultrasound and to determine thetransmission directivity. Herein, to the transmission delay circuit 6B,a trigger coming from the trigger signal generator 19 is supplied as atiming signal via the timing signal generator 18. In the pulser 6C,voltage pulse application is made on a channel basis to the probe 4 atthe timing of a rate pulse received from the transmission delay circuit6B. Responding to this pulse, the piezoelectric transducer of the probe4 is driven, and ultrasonic beams are generated for transmission to thesubject.

Herein, responding to the selection of MTT mode using the mode shiftswitch 16, scanning is started by the scan sequence that has beenprogrammed in advance with inter-frame transmission intervals.

The reflected waves transmitted as above and reflected bydiscontinuously arranged planes of acoustic impedance in the subject arereceived by the probe. Thus received reflected waves are output as echosignals on a channel basis, and captured into the ultrasound receptionsection 5.

The ultrasound reception section 5 is provided with a preamplifier 5A,an A/D converter 5B, a reception delay circuit 5C, and an adder 5D. Thepreamplifer 5A amplifies, on a channel basis, the echo signals thuscaptured into the ultrasound reception section 5 via the probe 4. Thusamplified echo signals are provided with the delay time needed todetermine the reception directivity by the reception delay circuit 5C,and then subjected to addition in the adder 5D. Such an additionresultantly enhances the reflection components from the directioncorresponding to the reception directivity of the echo signals. By thereception directivity and the directivity at the time of transmission,the comprehensive directivity for ultrasound transmission and receptionis determined. This comprehensive directivity is generally referred toscanning lines. The echo signals having been subjected to such a seriesof processes are forwarded from the ultrasound reception section 5 tothe receiver section 7.

The receiver section 7 goes through phase detection to extract signalsof any desired frequency band using an echo filter. Herein, thusextracted data is referred to as IQ data, and the IQ data is forwardedfrom the receiver section 7 to the B-mode unit 30 or a color flowmapping (CEM) unit 9.

The B-mode unit 30 is structured by an envelop detection circuit 30A anda logarithmic transformation unit 30B. The envelop detection circuit 30Adetects any envelop of an output signal coming from the receiver section7. The resulting data detected as such is referred to as B-modedetection data. The logarithmic transformation unit 30B applies acompression process to the B-mode detection data using logarithmictransformation. Note here that, in the following description, signalsbefore such envelop detection and logarithmic transformation arereferred to as IQ data, and data after such envelop detection andlogarithmic transformation are referred to as B-mode raster data.

Although not shown, the color flow mapping (CFM) unit 9 is structured bya phase detection circuit, an analog/digital converter, an MTI filter,an autocorrelator, and an arithmetic unit. Thereby, the blood flowcomponents are extracted by Doppler effect, and blood flow informationsuch as average speed, variance, and power are derived for variouspoints. The blood flow information is forwarded to the display section21 via the CFM mode DSC section 10, and the memory synthesis section 11,and then color-displayed as an average speed image, a variance image, apower image, and a combination image thereof.

As a control nerve in the entire system, the control circuit (CPU) 20applies control relating to the operation of the present ultrasonicdiagnostic apparatus, especially control relating to ultrasonic imagediagnosis by intermittent transmission, which will be described later.

The TIC/MTT measurement section 25 performs measurement of a TIC (TimeIntensity Curve: time-intensity change curve) and an MTT (Mean TransitTime: mean transit time) based on the RF data and others having beensubjected to phase addition by the adder 5D but not yet subjected to theprocess by the receiver section 7. The TIC/MTT measurement process to beexecuted by the TIC/MTT measurement 25 as such will be described laterin detail.

Both the B-mode digital scan converter (DSC) section 8 and the CFMdigital scan converter (DSC) section 10 convert a string of ultrasonicscanning line signals that have been input from the B-mode unit 30 intodata of orthogonal coordinate system based on spatial information. Atthe time when data transmission is carried out from the memory synthesissection 11 to the display section 21, video format conversion isperformed.

The memory synthesis section 11 synthesizes, into a frame, textinformation of various setting parameters, scales, or guidance imagesthat will be described later, and others. Then, applied is theconversion process into a string of scanning line signals of generalvideo format typified by televisions, and the like, and the result isoutput to the display section 21 as video signals.

On the display section 21, displayed as images are the morphologicalcompromise and blood flow information in the living body. When thecontrast agent is used, displayed on the display section 21 areintensity images and color images based on the spatial distribution ofthe contrast agent, that is, quantitative information volume as a resultof deriving regions in which any blood flow or blood is observed. Theframe memory 12 is provided for storage of digital data output of thememory synthesis section 11.

The storage section 27 is storage means for storing, on the basis ofdepth D, the acoustic fields V each indicating the spatial size againstthe sound pressure that can collapse and vanish the very-small bubbles.Herein, the value of acoustic field V is determined by measurement inadvance or simulation while controlling the parameters of ultrasound tobe irradiated from the probe 4 such as frequency, focus point, and MIvalue. The storage section 27 may be in any form as long as capable ofstoring electrical data, for provision, such as hard disks, FDs, CDs, orMDs.

TIC/MTT Measurement

Described next is the TIC measurement process and the MTT measurementprocess to be executed by the present ultrasonic diagnostic apparatus.Herein, the TIC and MTT measurement processes are both executed by theTIC/MTT measurement section 25 under the control of the CPU 20.

FIG. 3 is a flowchart showing the process procedure of the TIC/MTTmeasurement to be executed by the present ultrasonic diagnosticapparatus. FIG. 4 is a diagram for illustrating TICs and MTTs derived bythe TIC and MTT measurement processes.

In FIG. 3, first, scanning is performed under the contrast echo (stepS1).

Note here that the contrast agent currently in use for ultrasound isgenerally composed of very-small bubbles. Accordingly, it is collapsedor vanished if exposed to ultrasound for imaging, and thus continuousscanning is not appropriate thereto as is popular for any other medicalimage equipment. In the present ultrasonic diagnostic apparatus,scanning of step S1 is performed based on such a sequence as shown inthe upper part of FIG. 4, for example.

(1) First, injection of the contrast agent is started. The contrastagent is gently injected into a vein on a measured amount basis(alternatively, bolus injection is a possibility, and in this case, waituntil the contrast agent concentration becomes stable by blood flowcirculation).

(2) Next, the ultrasonic probe is placed at any position consideredappropriate, and then after transmission and reception, the very-smallbubbles in the observation area are collapsed for resetting.Alternatively, the very-small bubbles are collapsed for resetting whileaiming the blood vessel being a supply source from which the contrastagent is provided for the observation area (time t0 of FIG. 4). At thistime, if the very-small bubbles are fully filled, the harmoniccomponents derived at this time will be the maximum value of thereceiving echo signal.

(3) As shown in FIG. 4, transmission is stopped (temporarily stopped)only for a desired time interval t0, and when the set time comes,transmission and reception is performed for a frame. In this manner,derived are the harmonic components from the very-small bubbles so farflown into. Such transmission and reception is performed for a pluralityof times with respect to any one specific cross section. Herein, theultrasound transmission with any desired time intervals as such isreferred to as the intermittent transmission or flash echo (Flash Echo).With such intermittent transmission, to diagnose abdominal regions, forexample, it is preferable to set the transmission temporary-stop period,which is after the scanning is performed for the first time, generallyto 5 seconds or less, and preferably, to 3 seconds or less. In anexemplary case where the abdominal regions are diagnosed, thistransmission temporary-stop period can be measured by the internalcounter provided to the ultrasonic diagnostic apparatus 100, and if withcirculatory organs, by the ECG 1.

According to such intermittent transmission, any organ to be diagnosedis exposed to the ultrasound after the contrast agent for ultrasound isfully filled therein to aggressively collapse and vanish the contrastagent. In such a manner, derived is a strong signal from the very-smallbubbles. Here, scanning repeated for a plurality of times with respectto the same cross section is referred to as multishot. Such multishotcan cancel the effects caused by the remaining very-small bubbles.

(4) By going through transmission and reception described above, thevery-small bubbles in the observation area are collapsed and vanished.It is then considered that resetting is done, and transmission isresponsively stopped only for the time interval different from that forthe last time. Then, when any desired time that has been newly setcomes, transmission and reception is carried out for a frame so as toderive the harmonics components.

(5) The above-described (3) and (4) are repeated with variousintermittent time intervals to collect frame information of varyingtransmission-stop time intervals.

Here, in the present ultrasonic diagnostic apparatus, other than theabove-described scan sequence, the scan sequence for shortening theTIC/MTT measurement time can be also executed. Thereabout, a descriptionwill be given below.

Next, in FIG. 3, region designation is made to a region of theultrasonic image displayed on the display section 21 for assessment bythe TIC measurement or the MTT measurement (in the below, referred to as“assessment area”)(step S2). This designation is carried out respondingto inputs coming from the mouse 13, the track ball 14, and others in theoperation panel 15.

Next, with respect to the data (RF data in the first embodiment)corresponding to the assessment area of the echo signal collected forevery ultrasonic image through scanning in step S2, the TIC/MTTmeasurement section 25 calculates a representative value of theconcentration (intensity value). By plotting the resultingrepresentative value on the coordinate plane in which the vertical axisdenotes concentration, and the lateral axis denotes the intermittenttransmission time, derived is such a TIC as shown in the middle part ofFIG. 4, for example (step S3). The resulting TIC is displayed on thedisplay section 21 via the memory synthesis section 11. In this step,the TIC measurement process in S3 is executed based on the echo signalsnot yet subjected to logarithmic compression by the logarithmictransformation unit 30B. Further, steps S2 and S3 may be executed at thesame time.

Note here that the contrast agent generally varies in signal valuedepending on the administration concentration, dosage, dosing speed, ordue to varying tissue characteristics on an individual basis, or due tothe capability difference among the ultrasonic diagnostic apparatuses.Thus, there is no point in the absolute values of the signal valuesfound in the TIC. Generally used for assessment are the values relativeto the reference values, parameters exemplified by time-varyingintensity, and the like.

In the present embodiment, the TIC/MTT measurement section 25 goesthrough the TIC measurement process based on the RF data. In additionthereto, in each embodiment that will be described later, in this stepS3, the TIC/MTT measurement section 25 applies the process to each dataincluding: IQ data (data having been subjected to phase detection by thereceiver section 7 but not yet subjected to the process by the B-modeunit 30 or the CFM unit); B-mode detection data (data having beensubjected to envelop detection by the envelop detection circuit 30A butnot yet subjected to logarithmic transformation by the logarithmictransformation unit 30B); B-mode raster data (data having been subjectedto envelop detection and logarithmic transformation by the B-mode unit30 but not yet subjected to orthogonal transformation by the DSC section8); and B-mode orthogonal transformation data (data having beensubjected to orthogonal coordinate transformation by the B-mode DSCsection 8).

Next, the TIC/MTT measurement section 25 goes through MTT measurementbased on the TIC (step S4). Using the standardized TIC standardized bythe saturation value (maximum concentration value) in the TIC shown inthe lower part of FIG. 4 will lead to MTT. To be specific, in thestandardized TIC of FIG. 4, MTT is derived by the area of area S (thediagonally shaded area shown in the standardized TIC of FIG. 4. In thebelow, referred to as “MTT area”.) enclosed by the administrationstarting time of the contrast agent, the maximum value 1 at the timebefore reaching the saturation value, and the standardized TIC. The MTTarea may be, structurally, automatically device-designated by the CPU 20based on information about the TIC, or may be set by an operator using amanual through the mouse 13, the track ball 14, and others in theoperation panel 15.

Herein, the unit of the MTT thus derived by the standardized TIC of FIG.4 is a second. This MTT can be calculated not only from the standardizedTIC but also from the not-standardized TIC found in the middle part ofFIG. 4. That is, in the TIC in the middle part of FIG. 4, calculationmay be done by standardizing, by a saturation value, an area derived forthe area enclosed by the maximum value and the TIC in the range from therising time of the TIC (the time when signal detection from the contrastagent is started) to the time reaching the saturation value.

Moreover, in the TIC/MTT measurement section 25, not only the TIC/MTTmeasurement, the bioinformation exemplarily shown below can be alsomeasured.

The graph found in the lower part of FIG. 5 shows bioinformation MTB(Mean Transit Beat) measurable by the TIC/MTT measurement section 25. Inthe MTB, the vertical axis denotes the concentration, and the lateralaxis denotes the heart rate. To measure such MTB, in steps S1 and S2 ofFIG. 4, executed is the process similar to the case of MTT measurement,that is, the flash echo in which the transmission interval issynchronized with the ECG 1 (refer to the graph found in the upper partof FIG. 5). Then, in step S3, based on the signal measured by the ECG 1,the representative value derived for every image may be plotted onto thecoordinate plane in which the vertical axis denotes the concentration,and the lateral axis denotes the heart rate. This MTB is thebioinformation to be generated by parameters being individually uniquebut not the absolute time, exemplified by assessment of cardiac temporalphase (e.g., the last period of contraction, the last period ofexpansion), standardization by the heart rate, and the like.Accordingly, using such an MTB expectably leads to effects of removingthe susceptibility caused by varying heart rate for every individual dueto each different age and body shape.

As described in the foregoing, in the TIC/MTT measurement processexecuted by the TIC/MTT measurement section 25, used are signals beforecompression by logarithmic transformation. Accordingly, TIC/MTTmeasurement can be carried out with accuracy thanks to abundantinformation, without suffering from the effects of less data informationvolume reduced due to logarithmic compression.

Furthermore, as shown in FIG. 4, the TIC based on signals beforelogarithmic compression will be ideally more linear. Thus, it ispossible to carry out a fitting process more easily than theconventional case.

(Compensation Function)

Described next is the enhancement function of the present ultrasonicdiagnostic apparatus in the TIC/MTT measurement.

The present ultrasonic diagnostic apparatus has a function ofcompensating any effects to the MTT caused by beam form, especially theeffects to the MTT caused by beam difference in the depth direction.With this function, the TIC/MTT measurement can be carried out withhigher reliability.

FIGS. 6A, 6B, and 6C are all a diagram for illustrating the compensationprocess to be executed to the resulting MTT. As shown in FIG. 6AA, theshape of the ultrasonic beam coming from the prove 4 is not constant,and varies depending on the depth. For example, in a one-dimensionalarray probe, focus adjustment is done in the slice-thickness directionby a lens, and thus the beam thickness varies depending on the depth.Accordingly, as shown in FIG. 6B, even if the contrast agent isuniformly distributed, a difference is observed between the TIC as aresult of measurement based on the echo signal coming from a region A ofa subject (in the below, referred to as A-TIC) and the TIC as a resultof measurement based on the echo signal coming from a region B thereof(in the below, referred to as B-TIC).

In view thereof, in the present ultrasonic diagnostic apparatus,compensation is applied to the MTT in such a manner as to adjust theshape of the beam irradiated from the ultrasonic probe 4 depending onthe depth. For example, when the region B being the focus point is usedas a reference, as shown in FIG. 6C, variation of the MTTs caused by theacoustic fields varying depending on the depth is compensated bymultiplying the MTT derived by the A-TIC (in the below MTTA) by thesample volume of the acoustic field having the sound pressure capable ofcollapsing and vanishing the very-small bubbles or higher. In moredetail, assuming that the sample volume of the acoustic field capable ofcollapsing and vanishing the very-small bubbles in the referentialregion B is VB, and the sample volume of the acoustic field capable ofcollapsing and vanishing the very-small bubbles in the compensatingregion A is VA, VB/VA is integrated into the MTT value derived in theregion A. In this manner, variation of the MTTs caused by the beam shapecan be compensated. Such a compensation process is executed by the CPU20 reading a compensation coefficient corresponding to the transmissionrequirement from the storage section 27 to multiply the MTT thereby.

As such, by applying compensation to the MTT in such a manner as toadjust the shape of the beam irradiated from the ultrasonic probe 4depending on the depth, the MTTs can be prevented from varying,favorably leading to the better accuracy of quantitative assessment.

In a preferable structure, if an operator designates an assessment areathat has been firstly selected, using the designated position as areference, an area of almost spatially equal to the sound pressure withwhich the very-small bubbles can be collapsed and vanished is displayedon an image as shown in FIG. 7. Then, MTT assessment is allowed only tothe area. If this is the case, although limitation is imposed on theassessment area, it becomes possible to avoid the operator's erroneousassessment. Here, the frame data used for area selection is applied tothe one derived when the contrast agent is fully filled in the scanningcross section.

(Scan Sequence for Shortening TIC/MTT Measurement Time)

Described next is the scan sequence realized by the present ultrasonicapparatus for shortening the TIC/MTT measurement time. This scansequence is realized by the CPU 20 controlling the ultrasoundtransmission system (trigger generator 19, timing signal generator 18,and ultrasound transmission section 6) in accordance with a presetprogram.

Generally, if the blood flowing into the target tissue flows out afterpassing through the blood vessel system such as capillary tubes in thetissue in a controlled flow, the temporal change of the signal strengthideally shows a linear increase at where the TIC rises, and becomesconstant in value when the volume of the contrast agent is saturated bythe blood (refer to the lower part of FIG. 4 as an example).

Paying attention to this point, the present sequence performs MTTcalculation by deriving the saturation value, the initial value, and thegradient of the rising part of the TIC to obtain the rising time, andthe time of reaching the saturation value. Accordingly, withoutobtaining any sample point covering all, TIC/MTT creation is done fromthe rising part of the TIC. Thus, this successfully shortens the timetaken for data collection.

FIG. 8 is a diagram for illustrating the scan sequence to be executed bythe present ultrasonic diagnosis apparatus, and the TIC as a result ofmeasurement based on the echo signal derived by the scan sequence.

In the graph found in the upper part of FIG. 8, the vertical axisdenotes the strength of sound pressure, the lateral axis denotes thetime, and arrows each indicate cross section scanning. In the samegraph, a time range from t0 to t1 indicates the general scan sequence ofcontinuous transmission such as B-mode and color mode, and the time t1and onward indicates the present scan sequence of intermittenttransmission for TIC/MTT analysis. Here, the general scan sequence meansthe scan sequence for general imaging, the scan sequence for vanishing,collapsing, and refreshing the contrast agent in the scanning crosssection, or the like.

To make the following description more specific, in the graph at theupper part of FIG. 8, with the assumption that the contrast agent issaturated in 20 [seconds], created from the time t1 and onward is theTIC covering 20 [seconds]. Note that, under the conventional technique,if TIC creation is done by such a sampling time as increasing by 1[second], the very-small bubbles being the contrast agent may vanish andcollapse for every scanning, resultantly requiring resetting. Thus, ittakes 1+2+3+ . . . +20=210 [seconds] in total.

In the graph at the upper part of FIG. 8, first the contrast agent forultrasound is injected. Injection of this contrast agent is started attime t1. Alternatively, the contrast agent may be continuously injectedinto a vein before time t1 to complete injection at time t1 with gentleinjection into blood on a measured amount basis. After time t1, waituntil the very-small bubbles fully fill the scanning cross section (inthis case, until time t2. The time interval between the times t1 and t2is at least 10 seconds or longer but 30 seconds or shorter, preferably).During this time, there is no need to perform ultrasound transmission.However, monitoring scanning at low sound pressure not to collapse andvanish the very-small bubbles is a possibility to observe how filling ofthe very-small bubbles is done in real time, or to control anydisplacement of the cross section.

Thereafter, at time t2 when filling of the very-small bubbles is fullycompleted, scanning is done at high sound pressure being theintermittent transmission for the first imaging. In more detail, thevery-small bubbles in the scanning cross section are collapsed andvanished to collect the frame data relating to the saturation value.Thus collected frame data includes both the harmonic components byvery-small bubbles collapsing and vanishing, and the harmonic componentsfrom the soft tissues in the living body. And the absolute additionvalues thereof are stored in the frame memory 12. Herein, this scanningmay be numerous-cross-section scanning (multishot scanning) for ensuringthe very-small bubbles to completely collapse and vanish.

Thereafter, at time t3 that is a second after time t2 (before thevery-small bubbles perfuse again), performed are scanning and datacollection for signal collection only from the soft tissues of theliving body. The frame data at this time t3 will be the initial value inthe TIC. In view of avoiding variation of data values, in an alternativestructure, scanning may be performed for a plurality of times at thesame intermittent transmission intervals to adopt the average valuethereof.

After time t3, intermittent transmission is automatically started inaccordance with the intermittent transmission sequence that has been setin advance. In the intermittent transmission at this time, intermittenttransmission with short time intervals is carried out at at least two ormore different time intervals. At this time, if allowed to select two ormore of intermittent transmissions in order from those having theshortest time intervals, the measurement time can be favorablyshortened. In view of such circumstances, in the present embodiment, asshown in FIG. 8, executed are the intermittent transmission after timet2 at a second interval, and the scan sequence at two seconds interval.

Here, as to the intermittent transmission to be carried out in orderfrom those having the shortest time intervals, it is preferable to carryout pulse transmission for a plurality of times with the same timeintervals. By increasing the sample number, the variation of data can besuppressed, and the accuracy can be increased.

The TIC/MTT measurement section 25 derives the time of reaching thesaturation time from the rising time of a point TIC intersecting at theinitial value, the saturation value, and the straight line being theslope in the specifically-derived intermittent time. Based thereon, TICcreation is performed to calculate the area corresponding to the MTT. Atthis time, such TIC creation based on the rising part of the TIC can beapplied with linear approximation. This is surely not restrictive, andan approximation method in consideration of system characteristics canbe applied. For example, a possibility may be generally-knownhigher-order function approximation, spline approximation, orexponential function approximation.

In accordance with the present scan sequence, assuming that ultrasoundtransmission is carried out once 20 seconds after injection of thecontrast agent, and then intermittent transmission is carried out forthree times each at one [second] intervals and two [seconds] intervals.If this is the case, scanning can be done by 20+(1+2)×3=29 [seconds]. Assuch, the MTT can be derived by going through the short-time scanning,thereby reducing the temporal load imposed on patients and operators.

Herein, to shift into the scan sequence, it is preferable for theoperator to first check by monitoring scanning whether the contrastagent is filled over the scanning cross section, and if so, he or sheactivates the operation panel switch at any desired timing. In analternative manner, in accordance with a preset program, the scansequence is preferably started for MTT analysis automatically at anypredetermined time. Such automatic shifting is not restrictive, and inan alternative structure, the operator's manual operation will do. Ifthis is the case, to allow the operator to actively control shiftingfrom the initial state to monitoring scanning, and initial collection ofsaturation value data, considered is such a structure that depressingswitches of the operation panel will start such an operation.

Further, in the present scan sequence, it is possible to observe thedynamic behaviors of the contrast agent in real time by performing lowsound pressure scanning, i.e., monitoring scanning, not to collapse andvanish the very-small bubbles between times t1 and t2 in FIG. 8 asalready described.

FIG. 9 is a diagram for illustrating the TIC/MTT measurement utilizingthe monitoring mode (Monitor Mode). As shown in the upper part of FIG.9, monitoring scanning is performed from time t1 to t2. Alternatively,the resulting frame data may be previously stored in a storage mediumsuch as memory to perform TIC analysis. Or, simultaneous display is apossibility with the TIC derived by gradually changing the intermittenttransmission intervals. In this case, if the signal strength scale alongthe vertical axis is not the same, this increases the difficulty ofcomparative study. Thus, there needs to first standardize both by usingthe respective saturation values to perform display with the same scale.

The TIC based on this monitoring scanning is low in S/N. The issue hereis that, presumably, the result derived by standardizing the TIC by thesaturation value, and the result derived by standardizing the TIC, bythe saturation value, as a result of gradually-changed intermittenttransmission intervals ideally show each similar behaviors, and rendereach similar curves. There may be a case, however, that the very-smallbubbles may collapse and vanish at the time of monitoring depending onthe acoustic fields, the concentration of the contrast agent, and thetype of the contrast agent. In such a case, their rising parts have eachdifferent gradient, thus a possible application thereof is an index forsound pressure control at the time of monitoring.

In accordance with the present sequence, in the MTT analysis using thecontrast agent for ultrasound, it is possible to improve the accuracyand reliability, and to shorten the examination time. As a result,assessment can be carried out in an effective and efficient manner, andthe load to be imposed on patients and operators can be reduced, therebyleading to throughput increase.

(Effective Information Extraction Function)

Described next is the effective information extraction function providedto the ultrasonic diagnostic apparatus 100 of the present embodiment.The present ultrasonic diagnostic apparatus 100 performs TIC/MTTmeasurement with respect to echo signals extracted by this function.Here, this effective information extraction function is disclosed indetail in JP-A-2000-013563.

Generally, even if it is difficult to collapse and vanish the very-smallbubbles locating in the cross section by one-time scanning, utilizingmultishot performing scanning for various frames will vanish most of thevery-small bubbles in the scanning cross section in an effective manner.This means that using information about every frame data as a result ofmultishot will lead to information about almost all of the very-smallbubbles found in the cross section within the time of multishot.

Accordingly, it is possible to extract only information about anyeffective contrast agent to derive as a piece of frame data in thefollowing manner. That is, the information about frame data derived bymultishot is added for every coordinates, integration informationrelating to the contrast agent and the second harmonic components fromthe soft tissues of the living body, and then using the last frame dataof multishot, the accumulated value of the second harmonic componentsfrom the soft tissues of the living body is deducted. This is theeffective information extraction process, and in the present embodiment,the process is executed as follows based on the RF data for every frame.

FIG.10 is a conceptual diagram for illustrating such an effectiveinformation extraction process. As shown in the upper part of FIG. 10,assuming that the multishot number is 4, and the ith frame data of thenth multishot in the intermittent transmission is F(n, i)(in thisexample, i takes values of i=1, 2, 3, and 4), the frame data Fn havingbeen subjected to the nth effective information extraction process inthe intermittent transmission is denoted byFn=F(n, 1)+F(n, 2)+F(n, 3)−F(n, 4)×3   (1)Or, through expansion, denoted as $\begin{matrix}{{Fn} = {{{ps}\left\lbrack {{F\left( {n,1} \right)} - {F\left( {n,4} \right)}} \right\rbrack} + {{ps}\left\lbrack {{F\left( {n,2} \right)} - {F\left( {n,4} \right)}} \right\rbrack} + {{ps}\left\lbrack {{F\left( {n,3} \right)} - {F\left( {n,4} \right)}} \right\rbrack}}} & (2)\end{matrix}$Herein, the function ps[ ] executes the process that is previouslyoperator-designated or device-designated. For example, if ps[ ] isprovided with the parenthesized process in the mathematical calculation,the result will be equivalent to the equation (1).

When shadowing occurs, Fn may be a negative value in the equation (1)because tissue harmonics are deducted from the no-signal section.Therefore, because the signal strength is originally increased by thecontrast agent, this may impair quantitativity if the value is turnedinto positive. In such a case, preferably, the equation (2) is used toexecute the process in which ps[ ] replaces any value equal to orsmaller than a threshold value (e.g., 0) with 0.

As another technique, first a difference is taken between any twoframes, any value equal to or smaller than a certain threshold value(e.g., 0) is replaced with 0 in a similar manner to the above, and thensuch a statistic value as average or standard deviation value iscalculated. Utilizing such statistical values, any area in which thevery-small bubbles are vanished and collapsed enough to be assessed isdesignated as an assessable area by drawing a box therearound or bycoloring the same (opaque or transparent) to increase the reliability ofthe assessment value. For example, any area with a value having 70percent of the average value is regarded as the assessable area. Herein,such a numerical value as indicating percentage should be appropriatelydetermined empirically. Also, a determination is made whether thusdesignated assessment target ROI is locating in the assessable areawhile being included in the frame data derived by every intermittenttransmission being the assessment target. Only if determined as being inthe assessable area, the quantitative assessment is carried out.Alternatively, displayed may be a region previously multiplied over theframe data derived by every intermittent transmission being theassessment target.

During the scanning performed to derive the TIC, the scanning crosssection may be displaced due to the operator's unsteady hand(s) and thesubject's body movement (breathing included). Thus, an editing functionis preferably included for frame data selection.

By going through the above process, derived is an RF data cluster on aframe basis as a result of effective extraction of information about thevery-small bubbles in any target scanning cross section. Based on the RFdata cluster for every frame, the CPU 20 calculates the representativevalue in the assessment area set by the operator, for example, andexecutes the TIC/MTT measurement while controlling the TIC/MTTmeasurement section 25.

According to the above structure, even if the injection volume of thecontrast agent is high or the concentration thereof is high, detectionof blood flow perfusion, and the quantitative assessment of theperfusion can be carried out easily and effectively using the RF datanot yet subjected to a compression process.

Second Embodiment

In a second embodiment, shown is an ultrasonic diagnostic apparatus 102for executing a TIC/MTT measurement process based on IQ data (datahaving been subjected to phase detection by the receiver section 7 butnot yet subjected to the process by the B-mode unit 30 or the CFM unit).

FIG. 11 is a block diagram showing the structure of the ultrasonicdiagnostic apparatus 102 of the present embodiment. In FIG. 11, theTIC/MTT measurement section 25 receives the IQ data having beensubjected to phase detection from the receiver section 7 to go throughthe TIC/MTT measurement process. This TIC/MTT measurement process issimilar to the first embodiment. As to the effective informationextraction process utilizing the IQ data, it is possible to execute thatin a similar manner to the first embodiment.

With such a structure, the effects similar to the first embodiment canbe achieved. In the second embodiment, due to high-speed calculation andhardware limitation, the IQ data may be shorter in data length comparedwith the RF data (carry less information). If this is the case, it ispossible to reduce the calculation load. Further, by using the receiversection 7, any desired frequency components can be advantageouslyextracted.

Third Embodiment

A third embodiment shows an exemplary TIC/MTT measurement process to beexecuted based on B-mode detection data (data having been subjected toenvelop detection by the envelop detection circuit 30A but not yetsubjected to logarithmic transformation by the logarithmictransformation unit 30B).

FIG. 12 is a block diagram showing the structure of an ultrasonicdiagnostic apparatus 104 of the present embodiment. In FIG. 12, theTIC/MTT measurement section 25 receives, from the B-mode unit 30, theB-mode detection data having been subjected to envelop detection by theenvelop detection circuit 30A to go through the TIC/MTT measurementprocess. This TIC/MTT measurement process is similar to the firstembodiment. As to the effective information extraction process utilizingthe B-mode detection data, it is possible to execute in a similar mannerto the first embodiment.

With such a structure, the effects similar to the first embodiment canbe achieved.

Actually, the B-mode detection data is amplitude information withoutphase information. Thus, the data length thereof is much shorter thanthe RF data, and thus the calculation load is reduced in a practicalsense. Further, it is not having been subjected to data compression bythe logarithmic transformation unit 30B, thus no information reductionoccurs due to the compression process.

Fourth Embodiment

A fourth embodiment shows an exemplary TIC/MTT measurement process to beexecuted based on B-mode raster data (data having been subjected toenvelop detection and logarithmic transformation by the B-mode unit 30but not yet subjected to orthogonal transformation by the DSC section8). Specifically, in the first to third embodiments, the TIC/MTTmeasurement is carried out based on echo signals not yet subjected tologarithmic transformation (i.e., before compression). In the secondembodiment, shown is an exemplary TIC/MTT process to be executed byextracting intensity information before logarithmic transformation againthrough antilogarithmic transformation applied to detection signalshaving gone through the process in the receiver section 7.

FIG. 13 is a block diagram showing the structure of an ultrasonicdiagnostic apparatus 106 of the present embodiment. As shown in FIG. 13,the ultrasonic diagnostic apparatus 106 further includes anantilogarithmic transformation unit 26. This antilogarithmictransformation unit 26 receives, from the B-mode unit 30, B-mode rasterdata having been subjected to logarithmic transformation to performantilogarithmic transformation. The data as a result of decoding byantilogarithmic transformation and being put back to the echo signalhaving the linear signal strength is output to the TIC/MTT measurementsection 25. The TIC/MTT measurement section 25 goes through the TIC/MTTmeasurement based on thus input echo signal.

The TIC/MTT measurement section 25 goes through the TIC/MTT measurementin a similar manner to the first embodiment based on the data havingbeen subjected to antilogarithmic transformation.

The effective information extraction process utilizing the B-mode rasterdata after logarithmic transformation is as follows. That is, theantilogarithmic transformation unit 26 receives the B-mode raster datafrom the B-mode unit 30 responding to any predetermined operation tocarry out antilogarithmic transformation. The echo signal as a result ofdecoding by antilogarithmic transformation executed by theantilogarithmic transformation unit 26 is output to the TIC/MTTmeasurement section 25. Based on thus received echo signal, the TIC/MTTmeasurement section 25 calculates the representative value (e.g.,average value) in the assessment area designated by the operator, andthen based on the respective representative values, the TIC/MTTmeasurement is carried out.

With such a structure, the effects similar to the first embodiment canbe achieved. Even if the first to third embodiments are difficult due tohardware limitation, and thus if the B-mode raster data having beensubjected to logarithmic transformation and compression is used, linearfitting becomes possible at the TIC rising parts under the conditionthat the antilogarithmic transformation unit 26 applies data conversionthereto into linear. Accordingly, this eases regression calculation.

Fifth Embodiment

A fifth embodiment shows an exemplary TIC/MTT measurement process to beexecuted based on B-mode orthogonal transformation data (data havingbeen subjected to orthogonal coordinate transformation by the B-mode DSCsection 8).

FIG. 14 is a block diagram showing the structure of an ultrasonicdiagnostic apparatus 108 of the present embodiment. As shown in FIG. 14,the antilogarithmic transformation unit 26 receives, from the B-mode DSCsection 8, B-mode orthogonal conversion data to perform antilogarithmictransformation. The echo signal having been put back to the linearsignal strength by antilogarithmic transformation by the antilogarithmictransformation unit 26 is output to the TIC/MTT measurement section 25.The TIC/MTT measurement section 25 goes through the TIC/MTT measurementbased on thus received echo signal. This TIC/MTT measurement process issimilar to the first embodiment.

The effective information extraction process utilizing the B-modeorthogonal transformation data after logarithmic transformation is asfollows. That is, the antilogarithmic transformation unit 26 receivesthe B-mode orthogonal transformation data from the B-mode DSC section 8responding to any predetermined operation to carry out antilogarithmictransformation. The echo signal as a result of decoding byantilogarithmic transformation executed by the antilogarithmictransformation unit 26 is output to the TIC/MTT measurement section 25.Based on thus received echo signal, the TIC/MTT measurement section 25calculates the representative value (e.g., average value) in theassessment area designated by the operator, and then based on therespective representative values, the TIC/MTT measurement is carriedout.

With such a structure, the effects similar to the first embodiment canbe achieved. Even if the first to third embodiments are difficult due tohardware limitation, and thus the B-mode raster data having beensubjected to logarithmic transformation and compression is used, linearfitting becomes possible at the TIC rising parts under the conditionthat the antilogarithmic transformation unit 26 applies data conversionthereto into linear. Accordingly, this eases regression calculation.

Here, also in the ultrasonic diagnostic apparatuses according to thesecond to fifth embodiments described above, needless to say, thecompensation function and the effective information extraction functiondescribed in the first embodiment can be both realized.

Although a plurality of ultrasonic diagnostic apparatuses are shown, inview of calculation accuracy, as to the TIC/MTT measurement process, itis preferable to use output signals coming from any unit provided in theprevious stage as much as possible. This is because, as the unit isprovided to further subsequent stage, the data information volume of theoutput signal becomes less.

As such, the present invention is described by referring to theembodiments, and those skilled in the art can conceive numerousvariations and modifications within the scope of the present invention.Thus, those variations and modifications are understood as belonging tothe scope of the present invention, and can be devised without departingfrom the scope thereof.

Moreover, the above embodiments include inventions at various stages,and numerous inventions can be derived through appropriate combinationsof a plurality of disclosing components. For example, even if somecomponents are deleted from all of those shown in the embodiments, theobject mentioned in the section referring to the object to be solved bythe invention can be successfully solved, and when at least one effectof those mentioned in the section referring to the effects of theinvention is achieved, the structure from which the correspondingcomponent is deleted is derived as an invention.

According to the present invention described above, realized is anultrasonic diagnostic apparatus with which effects caused by the depthcan be reduced, and MTTs can be derived with assured accuracy and withhigh reproducibility through short-time scanning.

1-16. (canceled)
 17. An ultrasonic diagnostic apparatus, comprising: anultrasonic probe which applies ultrasound to an applied region of asubject having been injected with a contrast agent, and receives anultrasonic echo from the applied region; a driving signal generatorwhich generates a driving signal to drive the ultrasonic probe: acontrol unit which controls the driving signal generator on the basis ofa scan sequence, the scan sequence performing a first scanning with anultrasound of such a high intensity that the contrast agent iscollapsed, after a time at which the contrast agent is saturated in theapplied region, and performing a second scanning a plurality of times attime-varying time intervals after the first scanning, with theultrasound of such a high intensity that the contrast agent iscollapsed; and a processor which plots a time-varying graph ofconcentration of the contrast agent based on intensity of the ultrasonicecho under the saturation state of the contrast agent obtained by thefirst scanning and intensity of the ultrasonic echo at a rising point ofthe time-varying graph obtained by the second scanning.
 18. Theultrasonic diagnostic apparatus according to claim 17, wherein each ofthe time intervals at which the second scanning is performed a pluralityof times is half or less than half the time at which the contrast agentis saturated in the applied region.
 19. The ultrasonic diagnosticapparatus according to claim 17, wherein the processor acquires a meantransit time of a blood flow based on the time-varying graph.
 20. Theultrasonic diagnostic apparatus according to claim 17, wherein each ofthe time intervals at which the second scanning is performed a pluralityof times is half or less than half a period from a time based on alatest scanning with an ultrasound of such a high intensity that thecontrast agent is collapsed to a time at which the contrast agent issaturated in the applied region.
 21. An ultrasonic diagnostic apparatus,comprising: an ultrasonic probe which applies ultrasound to a hepaticregion of a subject having been injected with a contrast agent, andreceives an ultrasonic echo from the hepatic region; a driving signalgenerator which generates a driving signal to drive the ultrasonicprobe: a control unit which controls the driving signal generator on thebasis of a scan sequence, the scan sequence performing a first scanningwith an ultrasound of such a high intensity that the contrast agent iscollapsed, after a time at which the contrast agent is saturated in theapplied region, and performing a second scanning a plurality of times attime-varying time intervals set to be 3 seconds or shorter, after thefirst scanning, with an ultrasound of such a high intensity that thecontrast agent is collapsed; and a processor which plots a time-varyinggraph of concentration of the contrast agent based on intensity of theultrasonic echo under the saturation state of the contrast agentobtained by the first scanning and intensity of the ultrasonic echo at arising point of the time-varying graph obtained by the second scanning.22. The ultrasonic diagnostic apparatus according to claim 21, whereineach of the time intervals at which the second scanning is performed aplurality of times is half or less than half the time at which thecontrast agent is saturated in the applied region.
 23. An ultrasonicdiagnostic apparatus, comprising: an ultrasonic probe which appliesultrasound to an applied region of a subject having been injected with acontrast agent, and receives an ultrasonic echo from the applied region;a driving signal generator which generates a driving signal to drive theultrasonic probe: a control unit which controls the driving signalgenerator on the basis of a scan sequence, the scan sequence performinga first scanning with an ultrasound of such a high intensity that thecontrast agent is collapsed, after a time at which the contrast agent issaturated in the applied region, and performing a second scanning aplurality of times at time-varying time intervals after the firstscanning, with the ultrasound of such a high intensity that the contrastagent is collapsed; and a processor which plots a time-varying graph ofconcentration of the contrast agent, which is approximated linearly,based on intensity of the ultrasonic echo under the saturation state ofthe contrast agent obtained by the first scanning and intensity of theultrasonic echo at a rising point of the time-varying graph obtained bythe second scanning.
 24. The ultrasonic diagnostic apparatus accordingto claim 23, wherein each of the time intervals at which the secondscanning is performed a plurality of times is half or less than half thetime at which the contrast agent is saturated in the applied region. 25.An ultrasonic diagnostic apparatus, comprising: an ultrasonic probewhich applies ultrasound to an applied region of a subject having beeninjected with a contrast agent, and receives an ultrasonic echo from theapplied region; a driving signal generator which generates a drivingsignal to drive the ultrasonic probe: a control unit which controls thedriving signal generator on the basis of a scan sequence, the scansequence performing a first scanning with an ultrasound of such a highintensity that the contrast agent is collapsed, after a time at whichthe contrast agent is saturated in the applied region, and performing asecond scanning a plurality of times at time-varying time intervalsafter the first scanning such that a plurality of scanning operationsare performed each time, with the ultrasound of such a high intensitythat the contrast agent is collapsed; and a processor which plots atime-varying graph of concentration of the contrast agent based onintensity of the ultrasonic echo under the saturation state of thecontrast agent obtained by the first scanning and intensity of theultrasonic echo at a rising point of the time-varying graph obtained bythe second scanning.
 26. The ultrasonic diagnostic apparatus accordingto claim 25, wherein each of the time intervals at which the secondscanning is performed a plurality of times is half or less than half thetime at which the contrast agent is saturated in the applied region. 27.The ultrasonic diagnostic apparatus according to claim 25, wherein theprocessor plots the time-varying graph of the concentration of thecontrast agent by using a mean value of the ultrasonic echo obtained bysaid plurality of second scannings at each of the time intervals.
 28. Anultrasonic diagnostic apparatus, comprising: an ultrasonic probe whichapplies ultrasound to an applied region of a subject having beeninjected with a contrast agent, and receives an ultrasonic echo from theapplied region; a driving signal generator which generates a drivingsignal to drive the ultrasonic probe: a control unit which controls thedriving signal generator on the basis of a scan sequence, the scansequence performing a first scanning with an ultrasound of such a highintensity that the contrast agent is collapsed, after a time at whichthe contrast agent is saturated in the applied region, and performing asecond scanning a plurality of times at time-varying time intervalsafter the first scanning, with the ultrasound of such a high intensitythat the contrast agent is collapsed; and a processor which plots atime-varying graph of concentration of the contrast agent, which isnormalized by the saturation value of the contrast agent in the appliedregion, based on intensity of the ultrasonic echo under the saturationstate of the contrast agent obtained by the first scanning and intensityof the ultrasonic echo at a rising point of the time-varying graphobtained by the second scanning.
 29. The ultrasonic diagnostic apparatusaccording to claim 29, wherein each of the time intervals at which thesecond scanning is performed a plurality of times is half or less thanhalf the a time at which the contrast agent is saturated in the appliedregion.